2026-04-17T00:56:43Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1089752025-12-04T20:57:08Zcom_2072_1057col_2072_478796col_2072_478917

00925njm 22002777a 4500 dc Pastor, Isabel author Vilaseca i Font, Eudald author Madurga Díez, Sergio author Garcés, Josep Lluís author Cascante i Serratosa, Marta author Mas i Pujadas, Francesc author 2017-03-27T14:42:18Z 2017-03-27T14:42:18Z 2011 2017-03-27T14:42:18Z Traditionally, studies on the diffusion-controlled reaction of biological macromolecules have been carried out in dilute solutions (in vitro). However, in an intracellular environment (in vivo), there is a high concentration of macromolecules, which results in nonspecific interactions (macromolecular crowding). This affects the kinetics and thermodynamics of the reactions that occur in these systems. In this paper, we study the crowding effect of large macromolecules on the reaction rates of the hydrolysis of N-succinyl-L-phenyl-Ala-p-nitroanilide catalyzed by R-chymo- trypsin, by adding dextrans of various molecular weights to the reaction solutions. The results indicate that the volume occupied by the crowding agent, but not its size, plays an important role in the rate of this reaction. A vmax decay and a Km increase were obtained when the dextran concentration in the sample was increased. The increase in Km can be attributed to the slowing of protein diffusion, due to the presence of crowding. Whereas the decrease in vmax could be explained by the effect of mixed inhibition by product, which is enhanced in crowded media. As far as we know, this is the first reported experiment on the crowding effect in an enzymatic reaction with a mixed inhibition by product. Cinètica enzimàtica Macromolècules Inhibició Enzyme kinetics Macromolecules Inhibition Effect of crowding by dextrans on the hydrolysis of N-Succinyl-L-phenyl-Ala-p-nitroanilide catalyzed by α-chymotrypsin